Help identify this mysterious circuit

Thread Starter

Yami

Joined Jan 18, 2016
290
Hi, guys I was hoping that you could help me identify this circuit which I found cleaning out my workshop the other day. There is a brand name on the bottom which says "Kingtec" - searching online I still wasn't able to get any hint on what this circuit could be used for. It looks like it needs to be connected to a 12V battery.

Also another thing - I thought I'll sketch out the circuit, and I got quite confused with the pin out of the TO-3 package transistor. I have drawn a yellow circle on the side where the base pin on the transistor is . But then it would mean that the base of that transistor is connected to the ground or common of the circuit :S .
IMG_0065.JPG

IMG_0066.JPG

IMG_0067.JPG

Thanks in advance.
 

MaxHeadRoom

Joined Jul 18, 2013
20,911
KingTec appears to be into automotive products from refrigeration to lighting etc, it looks to be about 1980 vintage.
The board is marked tube, it could be some kind of old timing light system.
Max.
 

Thread Starter

Yami

Joined Jan 18, 2016
290
Thanks guys, and what about the T0-3 package transistor. The base is connected to the common right? Am I correct on how I identified the base of the transistor?
 

MaxHeadRoom

Joined Jul 18, 2013
20,911
WAAay back cars used to have a distributor for HV triggering of the plugs, the timing light was used in conjunction with a mark on the flywheel to strobe the mark and set the distributor for the correct plug-firing timing angle.
Using a Xenon tube for the flash.
Max.
 

Yaakov

Joined Jan 27, 2019
1,612
The board says choke, but by the number of connections it looks like it could be a transformer?
It is triggered by the 2n3055.
Just as you would need HV for a flourescent lamp.
Max.
It does appear to be an HV supply using the 2N3055 and the smaller transistor. The “choke” has two windings, and the output goes to the “tube” pad.
 

mvas

Joined Jun 19, 2017
537
Thanks guys, and what about the T0-3 package transistor. The base is connected to the common right? Am I correct on how I identified the base of the transistor?
It appears the 2N3055 Pins are offset towards the top screw, in your photo.
If true, then the yellow circle pin is the Emitter and
then the smaller transistor connects to the big transistor's base.
 

Thread Starter

Yami

Joined Jan 18, 2016
290
Wow, thanks guys for the help really appreciate it. Regarding the 2N3055 - can the part which has got the writing (part # etc) on it be rotated. Because looking at the datasheet when looked from top of the transistor the base should be on the left which would mean that base is connected to ground. This is where all the confusion started.
But like @mvas said looked from the bottom pins are offset towards the top screw which would means I have circled the emitter.
So can the top writing be oriented in any way during production, and is it not good to depend on it to identify the pins?

Thanks again
 

Yaakov

Joined Jan 27, 2019
1,612
So can the top writing be oriented in any way during production, and is it not good to depend on it to identify the pins?

Thanks again
The part number is NOT a guide to the pinout. It almost never will be because sometimes there isn’t even a part number visible. The case geometry, or an indexing mark is always the reference to the orientation when identifying pins. Logically, the base would be the one connected to the smaller transistor, so that’s also confirmation.
 
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